Pipe is used in countless applications in a wide variety of industries. In one application, "drill pipe" is used for drilling bore holes for crude oil recovery. Such drilling requires interconnecting many sections of drill pipe to form a "drill string" that may ultimately extend for more than one thousand feet under ground or under water.
As drill pipe sections are nominally 31 feet long and very heavy, their transportation to an offshore drilling platform can be costly and hazardous. Such transportation requires bundling the pipe at a land-based supply location, loading it onto a truck, delivering it to a dock, loading it onto a marine vessel, transporting it to the offshore platform and then unloading it for storage or use. Little can be done to circumvent such handling steps. But there is room for significant improvement in the apparatuses and methods that are used to secure such drill pipe for storage, handling and transport.
The method/apparatus most commonly employed for lifting and transporting drill pipe is to bundle the pipe with "choking slings." The bundled pipe is then lifted onto a truck, vessel, etc. using a crane. API Recommended Practices substantially limit the amount of pipe that can be handled per lift using such slings. As a result, the overall number of handling steps rapidly increase as multiple lifts are required at each stage as the pipe travels from supplier to platform. Such increased handling increases costs (e.g., labor costs, crane charges, etc.). Moreover, when tension on a loaded sling is relaxed, such as when the sling and pipes are deposited on a surface of a truck, marine vessel or drilling platform, the pipes are free to move in an uncontrolled manner presenting a risk of injury.
Specialized pipe storage/transportation apparatuses have been developed. Some of such apparatuses include spaced upright members that receive a plurality of cross members. Pipe sections are laid between such cross members (hereinafter "packing members") in an attempt to restrain such pipe segments from moving. Under harsh conditions, such apparatuses are often incapable of preventing slippage/movement of pipe. For example, the deck of a marine vessel may pitch ten to fifteen degrees in rough seas, thereby "tilting" such storage apparatuses. Under those conditions, there may be insufficient contact (i.e., frictional surface) between the pipe and packing members to prevent pipe slippage causing a potentially hazardous situation.
In one prior art storage/transportation apparatus, the pipe-receiving surfaces of packing members that are used to constrain pipe are not flat, but rather cycloid-shaped, as depicted in FIG. 1. Each pipe-receiving surface of packing member 100 includes a plurality of arc-shaped regions 102A, 102B (that collectively define the cycloid-shaped profile). Each of such regions 102A, 102B are configured to receive a "matched" diameter section of pipe 104 (two pipe sections 104 are depicted in FIG. 1). Two such packing members 100 are used to sandwich pipe sections 104. A "u-shaped" frame receives a plurality of such packing members 100 stacked one above the next so that multiple rows of pipe can be constrained.
In comparison with a prior art packing member having a flat pipe-receiving surface, arc-shaped regions 102 increase surface contact with the constrained pipe. The increased surface contact decreases the likelihood of pipe slippage.
As indicated above, packing member 100 is designed to fit a specific pipe diameter (e.g., 5-inch diameter or 41/2-inch diameter, etc.) as a function of the radius of curvature of arc-shaped regions 102. As such, a given packing member 100 is usable with only one size of pipe. Thus, if a load of pipe includes, for example, 3-inch, 41/2-inch and 5-inch diameter pipe, correspondingly-sized packing members are required to receive such pipe. Such specificity disadvantageously increases costs and presents the possibility that appropriately-sized packing members will not be available when needed.
As such, there is a need for an improved packing member, and a storage/transportation apparatus incorporating such a packing member, that is effective in restraining movement of elongate objects yet can cost effectively accommodate multiple object diameters.